Virtual reality (VR), augmented reality (AR), and mixed reality (MR) are becoming more popular due to their remarkable ability to alter a user's perception of the world. For example, VR, AR, and MR are used for learning purposes, gaming purposes, content creation purposes, social media and interaction purposes, or the like. These technologies differ in the user's perception of his/her presence. VR transposes the user into a virtual space so their VR perception is different from his/her real-world perception. In contrast, AR takes the user's real-world perception and adds something to it. MR is a combination of VR and AR.
These technologies are becoming more commonplace due to, for example, miniaturization of hardware components, improvements to hardware performance, and improvements to software efficiency. As one example, a user may experience VR content by using a head-mounted device (HMD) that encloses the user's field-of-view and is tethered to a computer. As another example, a user may experience AR content by wearing an HMD that still allows the user to see his/her surroundings (e.g., glasses with optical see-through).
As one example, the HMD tracks the user's eyes as an input for interactive AR/VR element. As another example, eye tracking is also used for contextual awareness as to the user's gaze direction or point of fixation. As yet another example, eye tracking is used to perform foveated rendering in order to reduce the resolution of out of focus content to decrease power consumption. As such, eye tracking is a useful input for the AR/VR experience. However, eye tracking is often accomplished with the use of light-emitting diodes (LEDs) fixed to the HMD. This increases the hardware cost and footprint associated with the HMD.
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